Helium-4 (1576 bytes)
1: ...lements is the source of most naturally occurring helium-4 on earth.
3: ...ehaviour is not explained by the [[chemistry]] of helium, but it is explained by [[quantum mechanics]].
4: ...eratures, because helium-3 is a [[fermion]] while helium-4 is a [[boson]].
8: <td width = 30% align = center>'''[[Helium-3]]'''
9: ...d width = 40% align = center>'''[[Isotope]]s of [[Helium]]'''

Helium-3 (4065 bytes)
1: ... use in [[nuclear fusion|fusion]]. More abundant helium-3 is thought to exist on the [[Moon]] (embedded i...
3: Helium-3 undergoes the following reaction, among others,...
7: ...tems from the nature of its reaction products. [[Helium-4]] is non-radioactive and the lone high-energy p...
9: Helium-3 is used in [[cryogenics]] to achieve temperatur...
11: ...id|superfluidity]]. The [[1970s]] discovery that helium-3 became a superfluid at around 2 millikelvins wa...

Helium (13541 bytes)
5: ...span="2" align="center" | [[hydrogen]] &ndash; '''helium'''
15: | Helium, He, 2
94: | [[Helium-3|³He]]
113: '''Helium''' is a colorless, odorless, tasteless [[chemical...
117: ...neral [[acid]]s. These samples were identified as helium by Lockyer and British physicist [[William Crooke...

Helium fusion (432 bytes)
1: ...he two involved [[atomic nucleus|nuclei]] being [[helium]].
3: ...e of [[red giant]]s and [[red supergiant]]s, then helium can fuse to form [[beryllium]] and then [[carbon]...

Liquid helium (2477 bytes)
1: ...critical point]] depend on the [[isotope]] of the helium; see the table below for values.
3: ...iquified in 1908 by [[Kamerlingh Onnes]]. Liquid helium-4 is commercially important today because of its ...
5: ...er by [[quantum]] effects, which are important in helium because of its low [[atomic mass]]. The [[zero p...
7: ...t sufficiently low temperature, both helium-3 and helium-4 undergo a transition to a [[superfluid]] phase ...
9: ..., the helium-4 rich phase may contain up to 6% of helium-3 in solution, which makes possible the existence...

Helium burning (675 bytes)
1: ...he [[alpha particles]] to produce [[oxygen]]. If helium fusion is left alone for awhile, it will produce ...

Helium-neon laser (3874 bytes)
1: A '''helium-neon laser''', usually called a '''HeNe laser''',...
6: <br><small>Schematic diagram of a helium-neon laser</small>
9: ...aser, as suggested by its name, is a mixture of [[helium]] and [[neon]] gases, approximately in the ratio ...
20: ...to a coincidence of [[energy level]]s between the helium and neon atoms.
28: ...ed states builds up as further collisions between helium and neon atoms occur, causing a [[population inve...

Exotic helium isotopes (1974 bytes)
1: ...han helium's natural isotopes, [[helium-3]] and [[helium-4]].
3: ... nucleus|atomic nuclei]] for [[element]]s such as helium, [[lithium]], and [[nitrogen]]. The bizarre nucle...
5: ...ecome an area of intense research. Isotopes up to helium-10, with two protons and ''eight'' neutrons, have...
7: ==Table of exotic helium isotopes==
15: |'''Helium-5'''

Heliair (431 bytes)
1: ...ting of mixture of [[oxygen]], [[nitrogen]] and [[helium]] and is often used during the deep phase of dive...
3: ...xygen and nitrogen with the balance consisting of helium.

Lambda point (222 bytes)
1: ... which [[helium]] I transitions to [[superfluid]] helium II[http://www.bartleby.com/61/68/L0026800.html].

Hydrogen-7 (882 bytes)
1: ...[helium-8]] atoms. In the resulting reaction, the helium-8's neutrons were donated to the hydrogen. The tw...

Dilution refrigerator (1994 bytes)
1: ...wo [[isotope]]s of [[helium]]: [[helium-3]] and [[helium-4]]. When cooled below 700 mK, the mixture underg...
3: ...rative cooling]], energy is required to transport helium-3 atoms from the ³He-rich phase into t...
4: ...sup>3</sup>He-poor phase cannot have less than 6% helium-3 at equilibrium, even at absolute zero, dilution...
6: ...ary into the ³He-poor phase. Once the helium-3 is all in the ³He-poor phase, the re...
8: ...power, and then into a [[still]] where the liquid helium-3 evaporates. Outside the refrigerator, this gas...

Cleveite (847 bytes)
3: ...ve and [[Abraham Langlet]] succeeded in isolating helium from cleveite at about the same time.

Isotope geochemistry (2537 bytes)
4: ===Helium-3===
5: [[Helium-3]] was trapped in the planet when it was created...
9: ... [[carbon]] in [[magma]] chemistry, outgassing of helium requires bubbling of [[carbon dioxide]], which ha...
11: Helium-4 is created by [[radiogenic]] production (by dec...
23: * [http://lvo.wr.usgs.gov/helium.html USGS: Helium Discharge at Mammoth Mountain Fumarole (MMF)]

Metal-poor (473 bytes)
1: ...ium]], and [[Metals]], i.e. elements heavier than Helium. '''Metal-poor''' objects thus contain very litt...

HPNS (424 bytes)
1: ...aused by using [[breathing gas]]es that contain [[helium]] at depths in excess of 130 metres / 429 feet.

Alpha reactions (973 bytes)
1: ... fusion|fusion reaction]]s by which stars convert helium into heavier elements, the other being the [[trip...
2: ...arbon]] is produced, other reactions that consume helium are possible:

Metalicity (324 bytes)
1: ... and Y denoting the mass fraction of hydrogen and helium.

Inflatable (645 bytes)
1: ...flated, usually with [[air]], but [[hydrogen]], [[helium]] and [[nitrogen]] are also used. The advantage ...
3: ...cy castle]]. The airship is usually inflated with helium as it is [[lighter than air]] and doesn't [[burn]...

Superfluid (2590 bytes)
3: ...minus;270.98 &deg;C). The less abundant isotope [[helium-3]] becomes superfluid at a much lower temperatur...
5: ...on]] in an interacting system. On the other hand, helium-3 atoms are [[fermion]]s, and the superfluid tran...
9: ... [[quantum solvent]]. Referred to as [[Superfluid Helium Droplet Spectroscopy]] (SHeDS), it is of great in...
12: * http://www.aip.org/png/html/helium3.htm

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